4 Things Americans Can Learn About Faith and Evolution From Great Britain and Canada


#332

A mathematical model does not necessarily correspond to reality. Your great faith in men is showing.


(Jon) #333

Unintentional irony.


(James McKay) #334

Yes, Bill, you are just guessing. I, on the other hand, gave you some actual calculations with the example of Betelgeuse that I cited, to show you that a sufficiently large gas cloud will easily fit within its gravitational potential well — even though it might be so tenuous that on earth it would be considered a near vacuum.

Now can you give me some actual calculations to show that the repulsive forces you postulate would disperse a gas cloud before it can collapse to form a star?

Are you able to demonstrate how the mathematical models under consideration deviate from reality, and that the difference would be large enough to support your conclusions?

I take it that the astrophysicist that you cite refers to this article by Jason Lisle.

His article is, quite frankly, a joke. You only need to have used a bicycle pump to be aware that his claim that “gas is very resistant to being compressed” is bovine effluent. Similarly, his claim that “in space, there is no container” completely disregards the concept of gravitational potential wells — which, as an astrophysicist, he should fully understand. As for his other assertions, he does not cite any calculations whatsoever to back them up.

You claim you’ve studied physics yourself. In that case, you should be familiar with the instruction given to every student of the subject at a very elementary level: Show your working.


#335

I like how of the 5 “References” only 2 are actually references and the other 3 are just comments. I suspect the 2 real references are quote mines.

I did have to laugh when I read this.

What holds the atmosphere to the earth? Are we surrounded by a giant container?


(James McKay) #336

I had a brief look at them (one is on arxiv.org, the other is partly available on Google Books). It’s not at all clear how they are supposed to support the points he claims that they make.

Update: OK I’ve had a closer look at the cited paper on arxiv.org rather than just the abstract. It is true that rotation, thermal pressure and magnetic fields will counteract the collapse of a stellar nebula. However, nowhere does the article suggest that these factors would stop stars from forming altogether. It merely states that the precise details of all the different scenarios haven’t been fully thrashed out.

Lisle’s argument basically boils down to “We know that the earth is young because there are things that we don’t know.” There are a lot of young-earth arguments that take this line and it is complete nonsense. Scientific findings are not falsified by unanswered questions but by contradictory data, and uncertainties in the fine details do not falsify the bigger picture.


(Jay Johnson) #337

Well said. Someone needs to inform the manufacturers of shock absorbers, as well.


(Phil) #338

@jammycakes, or anyone who knows, how does the temperature function in nebula? I assume that once a gas cloud expands, it must cool in the deep freeze of space and of course, a cool enough gas has very little gas pressure to overcome. Physics class was a long time ago, and what little astrophysics I know is from PBS.


#339

What story did they make up, and what evidence do you have to back this accusation?

The entire field of astrophysics disagrees with him, so I am not sure what you are getting at. Every single article I read sees no problems with gravitational collapse of gases to form stars.


#340

Followed by:

It seems that when the evidence contradicts your beliefs that you will suddenly call all scientific findings into question. However, when you think the science supports you, all of the sudden scientists are completely trustworthy. It’s a rather transparent attempt to ignore inconvenient evidence.


(George Brooks) #341

@Bill_Smith:

That’s just the point, Bill. The physics of 100 years ago was not fully understood … at the Cosmic and Galactic level.


(George Brooks) #342

@jpm

Once the net gravitational forces have reached a threshold, gas molecules begin to crowd together, eventually trumping the net loss of energy due to radiation when fusion is triggered due to molecular density.

If there is enough Gravity-Induced “crowding together” , all other forces are ultimately trumped.


(James McKay) #343

For a mathematical treatment, see the article on the Jeans instability on Wikipedia:

The two main concepts are the Jeans mass and the Jeans length. These represent the dimensions of a galactic nebula beyond which it becomes unstable and starts to contract to form stars. This article gives a couple of examples giving a Jeans mass of a couple of hundred solar masses or so, and a Jeans length of about a parsec. Many nebulae are far larger than that.

Rotation and magnetic fields will increase the effective Jeans mass and Jeans length, but they will not make them infinite.

Jason Lisle’s article does not even mention the Jeans mass and Jeans length — this is a very serious omission if he’s trying to debunk conventional models of stellar evolution because these concepts are absolutely fundamental to the subject. His claims that rotation and magnetic fields are a problem for stellar evolution are equivalent to claiming that they increase the Jeans mass and the Jeans length to values greater than those of any known galactic nebula. However, he does not give any mathematical justification for such a suggestion.


(Phil) #344

Even for a math impaired old guy, after re-reading that, it begins to make sense. Thanks for sharing!


(George Brooks) #345

@Jpm

Notice this text from the Wiki article:

" the British physicist Sir James Jeans … derived a formula for calculating this critical mass as a function of its density and temperature. The greater the mass of the cloud, the smaller its size, and the colder its temperature, the less stable it will be against gravitational collapse."

Notice that as a cloud of gas cools (just as you mentioned)… the more prone the cloud is to gravitational contraction! This makes sense, right? Hot gas has more molecular activity … with atoms banging into atoms … keeping the gas all nice and puffy.

But as the gas radiates its energy, and cools, there is less atom-against-atom activity, and the subtle inexorable forces of gravity begins to work its inescapable role: to organize chaotic gas into an organized fusion furnace!


#346

I will look into this more if I get time, and I am interested in it. Eventually I will probably get to it.

However, if you really want an answer to your objections, you can go to Jason Lisle’s blog or website or whatever he has. He answers questions there.